There has been significant scientific effort directed towards sequencing of DNA, proteins, and other target molecules. Such sequencing techniques often include amplification, where the target molecules must be processed so as to be concentrated, and further may include labeling of molecules as indicators.
Ionic current sensing schemes have been proposed and developed for amplification-free, label-free sequencing of DNA, proteins, and other target molecules. In one scheme, a single strand DNA with components arranged serially along the strand is passed through a nano-pore of a substrate. The ionic current is measured from one side of the substrate to the other side. When a particular component of the strand is in the nano-pore, the ionic current is reduced due to the presence of the component in the nano-pore. The amount of ionic current measured is based on the particular component present in the nano-pore. Thus, the target components of a DNA sequence may be identified to some extent based on measuring the ionic current.
This method of measuring the ionic current, however, lacks good specificity to the particular molecular component identified, and calibration is required for each nanopore. Further this method is interpretation error prone, and may have error rates of 15% or more.